Electronic teleconferencing is an economical way of bringing people together for conferences and meetings, without the costs, dislocations, delays and inconveniences associated with travel. In electronic teleconferencing, conferants sit in their own conference rooms and offices, and confer by conference call methodology. Typically, teleconferencing is supported by hard telefacsimile capability. However, teleconferencing systems, to be fully practical, must be capable of two way visual data communications. This requires digitizing visual information input and converting digital data to visual data, i.e., digitizing and displaying data as in a paperless telefacsimile. Recently electronic data transmission devices capable of digitizing and reproducing visual information manually entered upon a surface, e.g., an electrically communicative surface, have been developed and introduced. These devices constituted an independent parallel means of supporting teleconferencing.
The previous data transmission devices adapted for digitizing and reproducing information manually entered on a surface fall generally into one of two categories: digitizing tablet systems and electronic copyboards. Both of these devices possess significant technological limitations for two-way electronic data communications. Electronic copyboards lack the means, structurally and functionally, for reproducing incoming data from a remote location. Digitizing tablets, alone, are incapable of receiving and displaying data from a remote data input source.
Teleconferencing requires the use of one line for voice communications, one line for hand copy facsimile, and one line for data communications. Moreover, no means is provided for interaction between the lines.